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Stirling Engine from Kontax
Kontax Stirling Engine
Working Stirling Engine
A Stirling engine is one example of a broad class of heat engines which are devices designed to convert thermal energy into mechanical motion. The internal combustion, or gasoline, engine in an automobile is another example of a heat engine. The gasoline engine uses the combustion of fuel inside a confined volume, whereas the Stirling engine uses an external heat source to heat the working substance.

The heat source can come from burning fossil fuels (such as gasoline), solar energy, decaying plant matter, or even heat from a hand shown in the left picture. In this project a cup of hot water is used as my external heat source for the Stirling engine shown in the left bottom picture. In fact, all the Stirling engine requires to operate is a temperature difference across the top and bottom of the Stirling engine.

It is possible to run a Stirling engine by cooling one region of the engine below ambient temperature. The gas inside a Stirling engine is not burned or consumed in anyway. Hence, in contrast to the internal combustion engine, the Stirling engine does not require an exhaust or an intake. If a clean (green) external heat source is used with the Stirling engine, it can be an environmentally friendly alternative to engines that burn and emit hydrocarbons and other pollutants. Stirling engines also limit noise pollution because they do not require intake and exhaust valves which usually are the main source of engine noise. However, Stirling engines that would be suitable for automobile use are larger, heavier, and more expensive than conventional internal combustion engines. Moreover, Stirling engines require some time to warm up before they start, and the output of the engine can not be changed quickly for quick acceleration and deceleration. Although Stirling engines have not yet found use in the automotive industry, they have been used as a submarine engines. Recently, there has been a resurgence of interest in Stirling engines as the demand for more fuel efficient and clean engines continues to increase.

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created by Hiroko Nakahara
last modified: April 21, 2009